1. Field of the Invention
The present invention relates to a photovoltaic module, and particularly relates to a photovoltaic module including a filling material.
2. Description of the Related Art
Conventionally, a photovoltaic module including a filling material has been known (for example, refer to Japanese Unexamined Patent Application Publication No. 2001-119056). This application discloses a solar battery module (photovoltaic module) using a sealing material (filling material) difficult to deform at high temperatures, in order to cover the front and side surfaces of a solar battery device (photovoltaic device) and to fix the solar battery device and a transparent front protecting material (front surface protecting material) disposed on the front surface of the solar battery device. In the solar battery module, since the sealing material difficult to deform at high temperatures is used, the sealing material can be prevented from deforming by the force laterally applied to the transparent front protecting material when the temperature of the sealing material is high. This allows the transparent front protecting material to be prevented from being laterally displaced relative to the solar battery device.
However, the sealing material, used in the solar battery module disclosed in the above-described application, is difficult to deform even at high temperatures. As a result, when the solar battery is reused or a broken solar battery device is replaced, the sealing material is difficult to be removed from the solar battery device by heating the sealing material to a high temperature for softening it. Thus, it is difficult to reuse the solar battery device or to replace the broken solar battery device.
Therefore, a photovoltaic module capable of separating the photovoltaic module from the filling material of a lower soften temperature has been proposed. FIG. 1 is a cross sectional view showing the structure of the conventionally proposed photovoltaic module including the filling material having a low soften temperature. Referring to FIG. 1, the structure of the conventionally proposed photovoltaic module 101 will be described.
The conventional photovoltaic module 101 includes a plurality of photovoltaic devices 102 as shown in FIG. 1. Each of the photovoltaic devices 102 is connected with another adjacent photovoltaic device 102 via a tab electrode 103 made of a copper foil. The front, back, and side surfaces of the plurality of the photovoltaic devices 102 are covered with the filling material 104 made of a thermoplastic resin not including a cross linker. A front surface protecting material 105 made of glass board is disposed on the front surface of the filling material 104. The filling material 104 fixes the front surface protecting material 105. A back surface protecting material 106 is disposed on the back surface of the filling material 104. Frame members 108 are mounted on the side surfaces of the front surface protecting material 105, filling material 104, and the back surface protecting material 106 via an bonding layers 107.
According to the conventional photovoltaic module 101, since the thermoplastic resin not including the cross linker is used as the filling material 104, the soften temperature of the filling material 104 is lowered as compared with, for example, the case that a thermosetting resin including the cross linker is used as the filling material 104. This makes it possible to easily remove the fling material 104 from the photovoltaic devices 102 by heating the filling material 104 and softening it, for the reuse of the photovoltaic device 102 and the replacement of the broken photovoltaic device 102. Thus, it is possible to reuse the photovoltaic device 102 and to replace the broken photovoltaic device 102.
According to the conventional photovoltaic module 101 shown in FIG. 1, since the thermoplastic resin not containing a cross linker is used as the filling material 104, the soften temperature of the filling material 104 is lowered as compared with, for example, the case that a thermosetting resin containing a cross linker is used as the filling material 104. However, there has been a problem that the filling material 104 is easily deformed when the temperature of the filling material 104 becomes equal to or more than the soften temperature of the filling material 104. Therefore, the front surface protecting material 105 tends to be displaced laterally (in direction A) relative to the photovoltaic device 102, when a lateral (in direction A) force is applied to the front surface protecting material 105 disposed on the front surface of the filling material 104 in the state that the filling material 104 is easily deformed.